JP5218863B2 - Occupant detection system - Google Patents

Description

  The present invention relates to an occupant detection system that detects an occupant seated on a vehicle seat.

  2. Description of the Related Art Conventionally, a vehicle occupant detection system includes a mat-shaped electrostatic sensor and an occupant detection ECU (electronic control unit), and among these, the electrostatic sensor is disposed between a main electrode disposed inside a seat and a vehicle body. The generated weak electric field disturbance is output as a current or a voltage. An occupant detection system is described in, for example, Japanese Patent Application Laid-Open No. 11-271463 (Patent Document 1).

  For example, when the seat is empty, air is interposed between the pair of electrodes of the electrostatic sensor. Further, when a CRS (Child Restraint System) is mounted on the sheet, the CRS is interposed between a pair of electrodes of the electrostatic sensor. Further, when an occupant is seated on the seat, the occupant's human body is interposed between the pair of electrodes of the electrostatic sensor. Here, the relative dielectric constant of air is about 1. Further, although it depends on the material, the relative dielectric constant of CRS is about 2 to 5. Furthermore, the relative dielectric constant of the human body is about 50. Thus, the relative dielectric constants of air, CRS, and human body are different. Therefore, the capacitance between the pair of electrodes of the electrostatic sensor varies depending on the type of the insertion object.

  The weak electric field disturbance generated between the electrodes due to the difference in capacitance is output as current or voltage, and the occupant detection ECU performs occupant discrimination based on the output current value or voltage value. That is, the occupant detection ECU determines whether the seat is empty, whether a CRS (including a CRS on which a one-year-old child is riding) is mounted, or whether an adult is seated on the seat. Based on the determination result of the occupant detection ECU, the airbag ECU determines whether the airbag is permitted to be deployed / prohibited. Specifically, when the seat is vacant or when the CRS is attached to the seat, the airbag is set in a deployment prohibited state. On the other hand, when an adult is seated on the seat, the airbag is allowed to be deployed.

Japanese Patent Laid-Open No. 11-271463

  Here, there is a case where a heater for warming the sheet by passing a current through the conductor is disposed inside the sheet. In this case, the heater and the electrodes of the electrostatic sensor are arranged inside the sheet. The heater has a conductor through which a current flows, and affects a weak electric field between the electrodes. The occupant detection ECU is set so as to determine the occupant in consideration of the influence of the conductor of the heater.

  However, when the heater is disconnected, the influence of the heater conductor on the weak electric field changes. The occupant detection ECU is set to determine the occupant on the assumption that the heater is not disconnected. If the occupant determination is continued in the disconnected state, the occupant detection ECU may be erroneously detected.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an occupant detection system that can determine whether or not a heater disposed in a seat is disconnected.

  The invention according to claim 1, which has been made to achieve the above object, includes an electrode that is disposed inside a vehicle seat and generates a weak electric field, and a current or voltage corresponding to the magnitude of the weak electric field or a change thereof. An output value, a determination unit for supplying a voltage to the electrode, and determining an occupant of the seat based on the output value of the electrostatic sensor, in parallel with the electrode in the seat or the An occupant detection system that is disposed under the electrode and that heats the conductor by passing an electric current, wherein the determination unit determines an output value of the electrostatic sensor before determining the occupant of the seat. Based on the above, it is determined whether or not the heater is disconnected.

  According to this configuration, a weak electric field is generated between the electrode and the vehicle body (vehicle ground), and the occupant can be determined from the change in capacitance between the electrodes due to the presence or absence of the occupant. Here, when the heater is disconnected, the weak electric field between the electrodes changes. In this configuration, the change can be checked before occupant discrimination is started, and it can be detected that the heater is disconnected before occupant discrimination is started. That is, according to the present invention, it is possible to determine whether or not the heater is disconnected.

  According to a second aspect of the present invention, in the first aspect, the determination unit determines that the heater is disconnected when an output value of the electrostatic sensor is smaller than a preset threshold value. .

  According to this configuration, the disconnection of the heater can be detected by comparing the capacitance between the electrodes, which decreases due to the disconnection of the heater when the seat is empty, with a preset threshold value.

  According to a third aspect of the present invention, in the first aspect, when the output value of the electrostatic sensor becomes smaller than a preset threshold value, the determination unit again sets the output value of the electrostatic sensor again after a predetermined time. The threshold value is compared, and if the output value of the electrostatic sensor becomes smaller than the threshold value continuously for a preset number of times, it is determined that the heater is disconnected.

  According to this configuration, the determination unit determines that “there is a disconnection” only when the output value of the electrostatic sensor continuously falls below the threshold value a plurality of times. Therefore, more accurate disconnection determination is possible.

  According to a fourth aspect of the present invention, in the second or third aspect, the electrostatic sensor includes, as the electrode, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and the main electrode. And a guard electrode disposed oppositely and spaced below, and the discriminating section outputs an output from the sub electrode when a weak electric field is generated from the main electrode, the sub electrode, and the guard electrode. Whether the heater is disconnected or not is determined using the value as the output value of the electrostatic sensor.

  According to this configuration, the passenger is discriminated by generating a weak electric field from the main electrode, the sub electrode, and the guard electrode, for example, and the capacitance between the main electrode and the vehicle body and between the sub electrode and the vehicle body. Based on change. In this configuration, disconnection of the heater is determined based on a change in capacitance between the sub electrode and the vehicle body. According to this configuration, the guard electrode is not disposed below the sub-electrode, and the guard electrode does not get in the way of detecting disconnection of the heater disposed in parallel with the electrode or below the electrode. Therefore, the disconnection of the heater can be directly monitored, and the accuracy of determination is improved.

  According to a fifth aspect of the present invention, in the first aspect, the electrostatic sensor includes, as the electrode, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and a lower portion of the main electrode. And the guard electrode disposed oppositely and spaced from the main electrode, the sub-electrode, and the guard electrode when a weak electric field is generated from the main electrode, the sub-electrode, and the guard electrode, Whether or not the heater is disconnected is determined based on a ratio of output values from the sub-electrodes.

  According to this configuration, it is possible to determine disconnection based on the change in capacitance between the main electrode and the vehicle body and between the sub electrode and the vehicle body. Since the capacitance between the main body and the guard electrode is below the main electrode, the degree of change is small with respect to the disconnection of the heater. On the other hand, the capacitance between the sub-body does not have a guard electrode below the sub-electrode, and the degree of change is large with respect to the disconnection of the heater. That is, the ratio of both changes due to the disconnection of the heater. The determination unit can determine the disconnection by detecting this.

  A sixth aspect of the present invention is the method according to the second or third aspect, wherein the electrostatic sensor includes, as the electrode, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and the main electrode. And a guard electrode disposed oppositely and spaced below, and when the weakened electric field is generated from the main electrode and the guard electrode, the determination unit outputs an output value from the main electrode to the electrostatic sensor. It is determined whether or not the heater is disconnected as an output value.

  According to this configuration, when the heater is disconnected, the capacitance between the main body and the vacant seat is reduced, and the determination unit can detect the disconnection by detecting it.

  A seventh aspect of the present invention provides the method according to the second or third aspect, wherein the electrostatic sensor is a main electrode as the electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and the main electrode. Guard electrode disposed oppositely and spaced below, and when the discriminating unit generates a weak electric field from the main electrode, the sub electrode, and the guard electrode, an output value from the guard electrode The output value of the electrostatic sensor is used to determine whether or not the heater is disconnected.

  According to this configuration, it is possible to determine the disconnection of the heater by monitoring the change in the capacitance between the guard and the body. No electrode is arranged below the guard electrode, and the disconnection of the heater can be directly detected.

  The invention according to claim 8 further includes an alarm unit for notifying an occupant of a failure when the determining unit determines that the heater is disconnected, and determining the occupant when the determining unit determines that the heater is disconnected. It is characterized by stopping.

  According to this configuration, the occupant can confirm a failure in the occupant detection system, and erroneous detection is prevented by stopping the occupant determination.

1 is a configuration diagram illustrating a configuration of an occupant detection system 1. FIG. 2 is a schematic cross-sectional view showing an electrostatic sensor 2 and a heater 4. FIG. It is an equivalent circuit diagram of a detected object. It is a figure which shows the output value from the subelectrode. It is a figure which shows the processing flow of a disconnection detection mode. It is a figure when the output value from the subelectrode 22 is represented by ratio.

  Next, the present invention will be described in more detail with reference to embodiments.

<First embodiment>
The passenger | crew detection system 1 of 1st embodiment is demonstrated with reference to FIGS. First, the configuration of the vehicle seat will be described. As shown in FIG. 1, the seat 9 includes a seat surface portion 91 on which an occupant sits and a backrest portion 92 on which the occupant rests. A seat portion seat frame 91a that is electrically connected to the vehicle body A (vehicle ground) is provided at the bottom of the seat surface portion 91. Further, the backrest portion 92 is provided with a back seat frame 92 a that conducts to the vehicle body A.

  As shown in FIG. 1, the occupant detection system 1 mainly includes an electrostatic sensor 2, an occupant detection ECU 3 (corresponding to a “determination unit” in the present invention), a heater 4, and an alarm unit 5. ing.

  The electrostatic sensor 2 is a capacitance type sensor, and is formed in a sheet shape as a whole. The electrostatic sensor 2 is disposed inside the seat 9, specifically, between a skin (not shown) and a cushion above the seat surface portion 91.

  As shown in FIG. 2, the electrostatic sensor 2 includes a base film 2 a, a main electrode 21, a sub electrode 22, and a guard electrode 23. Specifically, the electrostatic sensor 2 includes a main electrode 21 and a sub electrode 22 on the seat surface portion 91 of the base film 2a, and a guard electrode 23 on the cushion side of the base film 2a. The main electrode 21 is disposed in a substantially wave shape over the entire base film 2a.

  The sub electrode 22 is spaced apart from the main electrode 21 and is disposed adjacent to the main electrode 21. The sub electrode 22 has a smaller surface area than the main electrode 21. The sub-electrode 22 is mainly used for detecting the wetness of the sheet 9 from the change in the capacitance between the main and the sub.

  The guard electrode 23 is disposed opposite to the main electrode 21 and is disposed between the main electrode 21 and the seat seat frame 91a. The guard electrode 23 has the same surface area as the main electrode 21. The guard electrode 23 is used to prevent the formation of an electric field between the main electrode 21 and the seat seat frame 92a.

  The occupant detection ECU 3 is an electronic control unit that mainly determines the presence or absence of the occupant or the type of the occupant. The occupant detection ECU 3 applies an AC voltage (sine wave) to the electrostatic sensor 2 at a predetermined timing. The electrostatic sensor 2 and the occupant detection ECU 3 are connected by a wire harness B.

  In the present embodiment, when detecting an occupant (occupant detection mode), the same voltage is applied to the main electrode 21, the sub electrode 22, and the guard electrode 23. However, the occupant detection mode can also be executed by applying a voltage to the main electrode 21 and the guard electrode 22. In addition, when detecting the moisture of the sheet (moisture detection mode), a voltage is applied to the sub electrode 22. The occupant detection ECU 3 selects the electrodes 21 to 23 to which the voltage is applied by switching a switch (not shown).

  Here, as shown in FIG. 3, an equivalent circuit of a detection object such as a human body or water detected by the electrostatic sensor 2 is a parallel circuit of resistance (real term: conductance) RMX and capacitance (imaginary term: susceptance) CMX. Shown in circuit. Accordingly, rather than detecting the electrostatic capacitance of the detected object, the impedance Z having the real term R and the imaginary term C is actually detected. When a sine wave is applied to this detected object from the occupant detection ECU 3, a potential difference is generated in a current detection resistor (not shown) in the occupant detection ECU 3 according to the impedance Z of the detected object. Here, when only the real term R exists in the impedance Z of the detected object, the potential difference generated in the current detection resistor does not include a phase lead component with respect to the signal source VSG (sine wave), and the signal source VSG When the potential difference generated in the current detection resistor is extracted at the real phase R sampling timing in the same phase, an output corresponding to the magnitude of only the real term R is obtained.

  Further, when only the imaginary term C exists in the impedance Z of the detected object, the potential difference generated in the current detection resistor includes a phase advance component with respect to the signal source VSG, and 90 ° with respect to the signal source VSG. When the potential difference generated in the current detection resistor is extracted at the advanced imaginary term C sampling timing, an output corresponding to the magnitude of only the imaginary term C is obtained. Since an actual detected object is composed of a real term R and an imaginary term C, it is measured as an impedance Z having the above phase.

  In this manner, the occupant detection ECU 3 measures the capacitance of the detected object on the seat 9 by the electric lines of force generated from the electrostatic sensor 2. That is, the current flowing through the current detection resistor in accordance with the supply signal from the sine wave is converted into a voltage.

  In the occupant detection mode, the occupant detection ECU 3 first measures the capacitance between the main electrode 21 and the vehicle body A, and then measures the capacitance between the sub electrode 22 and the vehicle body A. In other words, the occupant detection ECU 3 first connects the current detection resistor to the main electrode 21 and measures the output value from the main electrode 21. Thereafter, the occupant detection ECU 3 connects the current detection resistor to the sub electrode 22 and measures the output value from the sub electrode 22. In the present embodiment, in the occupant detection mode, a value obtained by adding the output values of both electrodes 21 and 22 is handled as the output value of the electrostatic sensor 2.

  Subsequently, the occupant detection ECU 3 switches to the moisture detection mode and measures the capacitance between the sub electrode 22 and the main electrode 21. In other words, the occupant detection ECU 3 provides a voltage only to the sub electrode 22, connects the current detection resistor to the sub electrode 22, and measures an output value from the sub electrode 22.

  The occupant detection ECU 3 stores a threshold value for determining an occupant and a threshold value for determining moisture. The occupant detection ECU 3 determines the occupant and the flooded water based on the output value of the electrostatic sensor 2 and the threshold value. As shown in FIG. 1, an airbag ECU 8 is connected to the occupant detection ECU 3, and the airbag ECU 8 determines whether the airbag 81 is in a deployment-permitted state or a deployment-prohibited state depending on the presence or absence and type of the occupant. Specifically, when it is determined that the seat is vacant or CRS is mounted, the airbag ECU 8 sets the airbag 81 in a deployment-prohibited state, and when it is determined that the seat is an adult seated state, the airbag 81 is set in a deployment-permitted state.

  The occupant detection ECU 3 further has a disconnection detection mode for detecting disconnection of the heater 4 (conductor 42), which will be described later in detail. The occupant detection ECU 3 sequentially executes each mode with the disconnection detection mode → the occupant detection mode → the wet detection mode as one cycle after activation.

  The heater 4 is configured by arranging conductors 42 (wires) in a wave shape with respect to a sheet-like base 41. As shown in FIG. 2, the heater 4 is disposed below the electrostatic sensor 2 via the urethane mat W inside the sheet 9. The heater 4 heats itself by passing an electric current through the conductor 42 to warm the sheet 9.

  The warning unit 5 is a lamp or the like provided at a position where an occupant such as a driver can visually recognize, and lights up according to a command from the occupant detection ECU 3 when the occupant detection ECU 3 determines that the disconnection has occurred. The alarm unit 5 can inform the occupant that the occupant detection system 1 has failed. The alarm unit 5 is provided in, for example, an instrument panel.

  Here, the disconnection detection mode will be described. The occupant detection ECU 3 applies a voltage to the main electrode 21, the sub electrode 22, and the guard electrode 23 in the disconnection detection mode. Then, the occupant detection ECU 3 connects the current detection resistor to the sub electrode 22 and measures the output value from the sub electrode 22. When the heater 4 is not disconnected, the sub electrode 22 forms an electric field with the vehicle body A.

  On the other hand, when the heater 4 is disconnected, an electric field is formed between the sub-electrode 22 and the conductor 42 portion that conducts to the vehicle ground due to the disconnection. As a result, the capacitance between the electrodes decreases when the seat is empty, and the output value from the sub-electrode 22 decreases.

  As shown in FIG. 4, when the heater 4 is disconnected at a position that is ¼ of the total length of the heater 4 from the power supply side (rear side of the vehicle), the output from the sub electrode 22 is reduced by approximately 1 pF. Moreover, when it disconnected at the position of 1/2 of the full length, it decreased by about 8 pF. Moreover, when it disconnected at the position of 3/4 of full length, it decreased about 15 pF.

  The occupant detection ECU 3 is set with a threshold value (hereinafter referred to as a failure threshold value) for determining the presence or absence of disconnection. In this embodiment, the failure threshold is set to −0.5 pF.

  Here, the processing flow of the present embodiment will be described with reference to FIG. When the ignition is turned on, the occupant detection ECU 3 first starts the disconnection diagnosis in the disconnection detection mode. The occupant detection ECU 3 supplies a voltage to each of the electrodes 21 to 23 and acquires an output value from the sub electrode 22 (S101). Subsequently, the occupant detection ECU 3 compares the output value with a failure threshold (S102). When the output value is larger than the failure threshold (S102: No), the occupant detection mode is entered and occupant discrimination is started.

  On the other hand, if the output value is smaller than the failure threshold (S102: Yes), it is checked whether or not the output value <failure threshold has continued N times (S103). N is a natural number of 2 or more. When the relationship of output value <failure threshold is less than N times (S103: No), the current output value of the sub-electrode 22 is acquired again and compared with the failure threshold (S101, S102).

  When the relationship of output value <failure threshold value continues N times (S103: Yse), the occupant detection ECU 3 determines that the heater 4 is disconnected. That is, the occupant detection ECU 3 determines that the heater 4 is disconnected only when the relationship of output value <failure threshold value continues continuously a plurality of times. Thereby, the reliability of disconnection determination improves.

  In the present embodiment, when the occupant detection ECU 3 determines that the disconnection has occurred, the occupant detection ECU 3 turns on the alarm unit 5 and stops the occupant determination. When the occupant detection of the occupant detection ECU 3 stops, the airbag ECU 8 connected to the occupant detection ECU 3 puts the airbag 81 in a deployment-prohibited state.

  Thus, according to the present embodiment, it is possible to detect disconnection of the heater 4 before occupant detection is started when the seat is empty. Since the guard electrode 23 is not disposed below the sub electrode 22 and the output value is greatly reduced due to disconnection, the occupant detection ECU 3 of the present embodiment can detect disconnection with high accuracy. Note that when the occupant is seated on the seat 9, the output value of the sub-electrode 22 increases, and thus disconnection cannot be determined in this embodiment. Even if the passenger enters the disconnection detection mode while seated, the output value from the sub-electrode 22 does not fall below the failure threshold and is not determined to be disconnected. Therefore, this embodiment is effective when, for example, the passenger seat is empty, or when the passenger in the passenger seat leaves the seat.

  The present embodiment is not limited to the above. For example, as shown in FIG. 6, the occupant detection ECU 3 may determine the disconnection based on the ratio to the output value in the state without disconnection. At the time of disconnection, the output value of the sub electrode 22 decreases, and the ratio decreases with respect to the state without disconnection. If the output value in the state without disconnection is 1, the output value at disconnection is less than 1. The occupant detection ECU 3 can determine the disconnection by storing the output ratio threshold.

  Further, the occupant detection ECU 3 may determine that a disconnection occurs if the relationship of output value <failure threshold is satisfied even once. Further, the electrode of the electrostatic sensor 2 may be only the main electrode 21. In this case, when the heater 4 is disconnected, the capacitance between the main electrode 21 and the vehicle body when empty is reduced, and the output value of the electrostatic sensor 2 is also reduced. Therefore, the occupant detection ECU 3 can determine the disconnection based on the output value of the electrostatic sensor 2. Similarly, the occupant detection ECU 3 may determine the disconnection based on the output value from the main electrode 21 in the disconnection detection mode in the present embodiment.

  The occupant detection ECU 3 may determine the disconnection based on the output value from the guard electrode 23 in the disconnection detection mode in the present embodiment. In the disconnection detection mode, the guard electrode 23 forms an electric field with the seat seat frame 91a (or / and the vehicle body A). Here, when the heater 4 is disconnected, the output value from the guard electrode 23 decreases as described above. In this case, the occupant detection ECU 3 connects the current detection resistor to the guard electrode 23 and measures the output value from the guard electrode 23 in the disconnection detection mode.

  Further, in this case, there is no other electrode below the guard electrode 23, and disconnection can be detected more directly. Specifically, the reduction degree of the output value is larger than the reduction degree of the main electrode 21, and the occupant detection ECU 3 can detect the disconnection with high accuracy.

<Second embodiment>
The second embodiment has the same configuration as that of the first embodiment, and the disconnection determination method of the occupant detection ECU 3 is different from that of the first embodiment. Therefore, 2nd embodiment is described with reference to FIG. 1 like 1st embodiment.

  The occupant detection ECU 3 supplies a voltage to the main electrode 21, the sub electrode 22, and the guard electrode 23 in the disconnection detection mode. The occupant detection ECU 3 first measures the output value of the main electrode 21 and then measures the output value of the sub electrode 22 as in the occupant detection mode. However, whichever comes first.

  Here, the degree of decrease in the output value when the heater 4 is disconnected differs between the main electrode 21 and the sub electrode 22, and the sub electrode 22 is larger. Using this, the occupant detection ECU 3 calculates the ratio between the output value of the main electrode 21 and the output value of the sub electrode 22 and compares it with a failure threshold of a preset ratio. Then, the occupant detection ECU 3 determines the disconnection based on whether or not the ratio of the output values is below (exceeds) the failure threshold.

  For example, when an occupant is seated on the seat 9, the output value of the main electrode 21 is approximately 150 pF, and the output value of the sub electrode 22 is approximately 50 pF. That is, in the normal state, the output value of the sub electrode 22 is about 1/3 of the output value of the main electrode 21 (main electrode 21: sub electrode 22 = 3: 1).

  On the other hand, when the heater 4 is disconnected, the output value of the main electrode 21 is slightly reduced and the output value of the sub electrode 22 is greatly reduced. Therefore, the output value of the sub electrode 22 is about 1/5 of the output value of the main electrode 21. (Main electrode 21: Sub electrode 22 = 5: 1). Here, when the failure threshold is set to, for example, ¼ (main electrode 21: sub electrode 22 = 4: 1), the failure threshold is exceeded at the time of disconnection, and disconnection of the heater 4 can be detected.

  Thus, the occupant detection system 1 of the second embodiment determines whether or not the heater 4 is disconnected based on the ratio of the output value from the main electrode 21 and the output value from the sub electrode 22. According to the second embodiment, even when an occupant is seated on the seat 9, the disconnection of the heater 4 can be detected.

1: Occupant detection system,
2: electrostatic sensor, 21: main electrode, 22: sub-electrode, 23: guard electrode,
3: Occupant detection ECU,
4: Heater, 5: Alarm section

Claims (8)

An electrostatic sensor that is disposed inside a vehicle seat and has an electrode that generates a weak electric field, and that outputs an electric current or voltage corresponding to the magnitude of the weak electric field or a change thereof;
A determination unit that supplies a voltage to the electrode and determines an occupant of the seat based on an output value of the electrostatic sensor;
A heater that is arranged in parallel with or under the electrode inside the sheet, and heats the conductor by passing an electric current;
An occupant detection system comprising:
The said discrimination | determination part discriminate | determines whether the said heater has disconnected based on the output value of the said electrostatic sensor, before discriminating the passenger | crew of the said sheet | seat.   The occupant detection system according to claim 1, wherein the determination unit determines that the heater is disconnected when an output value of the electrostatic sensor is smaller than a preset threshold value.   When the output value of the electrostatic sensor becomes smaller than a preset threshold value, the determination unit compares the output value of the electrostatic sensor with the threshold value again after a predetermined time, and continues for a preset number of times. The occupant detection system according to claim 1, wherein when the output value of the electrostatic sensor becomes smaller than the threshold value, it is determined that the heater is disconnected. The electrostatic sensor includes, as the electrodes, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and a guard electrode disposed so as to be opposed to and spaced below the main electrode. ,
Whether the heater breaks the heater using the output value from the sub electrode as the output value of the electrostatic sensor when a weak electric field is generated from the main electrode, the sub electrode, and the guard electrode. The occupant detection system according to claim 2 or 3 for determining whether or not. The electrostatic sensor includes, as the electrodes, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and a guard electrode disposed so as to be opposed to and spaced below the main electrode. ,
When the weak electric field is generated from the main electrode, the sub electrode, and the guard electrode, the determination unit determines whether the heater is based on a ratio between an output value from the main electrode and an output value from the sub electrode. The occupant detection system according to claim 1, wherein the occupant detection system determines whether or not a disconnection has occurred. The electrostatic sensor includes, as the electrodes, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and a guard electrode disposed so as to be opposed to and spaced below the main electrode. ,
The said discrimination | determination part discriminate | determines whether the said heater was disconnected using the output value from the said main electrode as the output value of the said electrostatic sensor, when the weak electric field was generated from the said main electrode and the said guard electrode. The occupant detection system according to 2 or 3. The electrostatic sensor includes, as the electrodes, a main electrode, a sub-electrode disposed so as to be separated from and adjacent to the main electrode, and a guard electrode disposed so as to be opposed to and spaced below the main electrode. ,
If the discriminator generates a weak electric field from the main electrode, the sub electrode, and the guard electrode, whether the heater is disconnected using the output value from the guard electrode as the output value of the electrostatic sensor. The occupant detection system according to claim 2 or 3 which discriminates. A warning unit for notifying the passenger of a failure when the determination unit determines that the heater is disconnected,
The occupant detection system according to any one of claims 1 to 7, wherein the determination unit stops occupant determination when it is determined that the heater is disconnected.

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